Article

New lightweight composite construction materials with low thermal conductivity

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  • Pathumthani University
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Abstract

This paper presents an initial investigation on the use of a new lightweight construction material, composed of cement, sand and fiber of waste from young coconut (Cocos nucifera) and durian (Durio zibethinus). Thermal conductivity, compressive strength and bulk density were investigated. The experimental investigation reveals that the addition of these fibers reduces the thermal conductivity of the composite specimen and yield a lightweight. The composite satisfies the basic requirement of construction materials, and they could be used for walls and roofs. Thus, the potential for development, therefore, seems to be very promising. Finally, apart from saving energy consumption for the building, the proposed materials offer an alternative option to dispose waste of fruit industry.

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... To achieve this goal, the partial replacement of cement by vegetable fibers as reinforcement of cementitious matrix is considered [1,3,6,7]. Indeed, vegetable fibers are known to have insulating properties that is to say a low thermal conductivity and appear to be a good alternative to synthetic fibers such as glass fibers or asbestos fibers, commonly used for building insulation [8][9][10]. As observed by On� esippe et al., in 2010 [3] and even now, few works have demonstrated the low thermal conductivity of vegetable fibers cement-based composites as well as the thermal conductivity of vegetable fibers (when they are incorporated in the composites) and the influence of moisture on thermal conductivity of these composites. ...
... As observed by On� esippe et al., in 2010 [3] and even now, few works have demonstrated the low thermal conductivity of vegetable fibers cement-based composites as well as the thermal conductivity of vegetable fibers (when they are incorporated in the composites) and the influence of moisture on thermal conductivity of these composites. The presence of wood fibers reduces the density of the material [11] and decreases its thermal conductivity [3,6,10]. ...
... Moreover, short fibers, as used in this study, are considered to be more difficult to align and pack densely. The packing of short fibers in cement paste leads to increase the amount of voids [10] and therefore porosity. ...
Article
Auto-coherent homogenization is used to evaluate the thermal conductivity of sugar cane bagasse fibers in vegetable fibers/cement composites. The moisture content effect on the thermal conductivity of composites is also studied. When the fiber content increases, porosity increases and bulk density and thermal conductivity of composites decrease. When the moisture content grows the thermal conductivity of composites increases. In dry state, there is a gap of less than 10% between experimental and modeled values. In wet state, there is a good agreement between estimated and experimental values of thermal conductivity of composites up to 4 %wt of fibers content.
... In terms of thermal conductivity, natural insulating materials have demonstrated to achieve excellent results with values ranging from 0.07 to 0.63 W/m.K for mortar reinforced with date palm fibres (Benmansour et al., 2014), hempcrete (Dhakal et al., 2017), gypsum boards (De Korte and Brouwers, 2010;Ghazi Wakili et al., 2015), wood shaving cement composites (Ledhem et al., 2000), biochar as a concrete filler (Cuthbertson et al., 2019), cement paste with silica fumes, methylcellulose and carbon fibres (Fu and Chung, 1997;Xu and Chung, 2000), coir-cement composites (Khedari et al., 2001;Brose et al., 2019;Mendes et al., 2019), and reinforced concrete using coir (Babafemi et al., 2019;Itagi and Annapurna, 2019). ...
... E. Quiñones-Bolaños et al. (Benmansour et al., 2014), hempcrete ranging from 0.07 to 0.10 W/m.K (Dhakal et al., 2017), and other studies on mortar modified by coconut fibres with values ranging from 0.18 to 0.93 W/m.K (Khedari et al., 2001;Brose et al., 2019;Mendes et al., 2019). The mechanical test results for coconut-fibre Portland cement mortars show that a conventional cement mortar has about 8.4 MPa compressive and 9.5 MPa flexural strengths, while for coir-modified mortars were 8.7 MPa and 10.5 MPa for compressive and flexural strengths, respectively. ...
... The mechanical test results for coconut-fibre Portland cement mortars show that a conventional cement mortar has about 8.4 MPa compressive and 9.5 MPa flexural strengths, while for coir-modified mortars were 8.7 MPa and 10.5 MPa for compressive and flexural strengths, respectively. These results indicate that the addition of coconut fibres to the conventional cement mortar can also improve the mechanical properties of the mortar (Khedari et al., 2001;Mendes et al., 2019). Fig. 7 shows temperature variations at five locations previously shown in Fig. 2, exterior front entrance (S1), second bedroom (S2), backyard (S3), master bedroom (S4) and living room (S5). ...
Article
Enhancing the thermal comfort of low-income housing in developing countries located in tropical areas is one of the main challenges for engineers and architects worldwide. The coconut mesocarp fibre (coir) has shown enormous potential for improving some properties of modified concretes or mortars, such as low-weight and high-acoustic isolation. In this study, the potential use of modified mortars by coconut fibres as a facade coating layer to enhance thermal comfort in low-income housing structures was evaluated for the city of Cartagena de Indias, Colombia. An actual typical low-income house of 42 m 2 was monitored. Temperature and humidity variations were monitored for 39 days, thermal characteristics of coir-modified mortars were also investigated using differential scanning calorimetry (DSC) and an adaptation of the standard test method of the guarded-hot-cartridge apparatus. The EnergyPlus™ software was used to simulate indoor temperature variations in the studied house. Results show that during the period of 4 h of maximum sunlight radiation with outdoor temperatures in the range of 29-34 • C, coating the cement-sand hollow block structure with a layer of coir-modified mortar could reduce indoor room temperatures by 0.5-1.5 • C, approximately. Thus, there is a potential to enhance the thermal comfort in low-income housing structures with coconut fibre modified mortars while reducing annual energy costs of cooling by 16%, making it affordable for low-income families in the Caribbean region of Colombia.
... Although some reduction in the compression strength was observed upon the addition of the natural fiber, approximately constant strength of 64 MPa was achieved with composites containing 30 wt% to 50 wt% date palm wood, see Fig. 12b. This value of compression strength exceeds the strength of all traditional insulations (compressive strength = 2 MPa and 10 MPa) [61] and is comparable with the strength of construction materials, such as concrete (40 MPa) and cement with natural pozzolan (60.8 MPa) [62][63][64]. It is expected that the natural fibers reduce the mechanical properties of composites due to the incompatibility between the filler and the polymer matrix [56,65]. ...
... The strength of PLA-DPWP composites is still higher than some proposed insulation materials (ultimate strength = 2.4-3.3 MPa) [61], and cement blocks containing insulating filler like mineral wool and sisal, where the strength was between 3 and 4.5 MPa [58]. Fig. 13a shows the morphology of the pure PLA surface, which can be recognized as brittle and rigid structure. ...
... As can be seen in Fig. 13b and c, increasing the filler content resulted in the agglomeration of DPWP particles (Fig. 13b and c). The presence of the interparticle hydrogen bonding in natural fibers such as date palm wood leads to the agglomeration phenomenon [61]. Moreover, the size of agglomerates increased at higher filler content, leading to a non-uniform dispersion of DPWP in PLA and to the creation of stress concentration points. ...
Article
A green polymer composite consisting of date palm wood powder (DPWP) and polylactic acid (PLA) was developed, as an insulating material. DPWP (10–50 wt%) was mixed with PLA in a melt extruder, followed by compression molding and annealing processes. The composites were investigated to evaluate their physical (density, water absorption and degree of crystallization), thermal (thermal conductivity, thermal diffusivity, glass transition and melting temperature) and mechanical properties. Moreover, the structure of the developed composites was characterized by FTIR, XRD and SEM techniques. The characterized properties of the PLA-DPWP composites, displayed that a thermally stable composite material with insulation and construction capacity can be produced by the addition of DPWP to PLA matrix. Addition of DPWP decreased the composite's thermal conductivity to a minimum of 0.0692 W/(m.K) at 30 wt.% DPWP contents. In addition, the thermal diffusivity decreased as filler contents were increased, reaching a minimum value of 0.036 mm2/s. Although the water absorption was observed to increase with DPWP contents, it showed very low values (less than 2%) compared to the conventional thermal insulation materials. The PLA-DPWP composites demonstrated superior compressive strength compared to commonly used insulating materials, which was comparable to some construction materials. A compressive strength of ∼65 MPa was measured for the composites with 30–50 wt.% filler contents. The results of this work revealed that PLA-DPWP composites have high potential as promising green thermal insulation material owing to their low thermal conductivity, thermal diffusivity, and water absorption while maintaining high mechanical strength. Therefore, recycling of DPWP waste, which is cheap, as filler materials for green thermal insulators, is of significant benefits to both the economy and environment.
... Nevertheless, Figure 6a shows that compared with other composites used in building walls, ceilings, and roofs, such as lightweight construction materials comprising cement, sand, and fibers of coconut and durian waste (2.4-3.3 MPa) the produced UPR-BR composites exhibited greater compressive strengths [26]. In addition, the compressive strength at 50 vol.% ...
... Nevertheless, Figure 6a shows that compared with other composites used in building walls, ceilings, and roofs, such as lightweight construction materials comprising cement, sand, and fibers of coconut and durian waste (2.4-3.3 MPa), the produced UPR-BR composites exhibited greater compressive strengths [26]. In addition, the compressive strength at 50 vol.% ...
Article
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Bauxite residue (BR) is one of the most commonly generated industrial wastes in the world. Thus, novel techniques for its proper utilization must be urgently developed. Herein, seawater-neutralized BR–unsaturated polyester resin (UPR) composites are presented as insulating construction materials with promising mechanical performance. Composites with different BR content (0–60 vol.%) were prepared to evaluate the influence of BR content on the compressive, tensile, and flexural strengths as well as the moduli of BR–UPR composites. Experimental results revealed that adding BR particles to the polyester matrix increased the compressive properties (strength, modulus, and strain). The composites containing 20 vol.% BR showed the maximum compressive strength (108 MPa), while the composites with 30 vol.% BR exhibited the maximum compressive modulus (1 GPa). Moreover, the reduction in tensile and flexural strengths with an increase in the BR content may be attributed to the lower efficiency of stress transfer between the BR particle–polyester interface due to weak adhesion at the interface, direct contact between particles, and presence of voids or porosity. Although the tensile strength and failure stress decreased with increasing filler content, the produced composites showed outstanding tensile strength (4.0–19.3 MPa) compared with conventional insulating materials. In addition, the composite with 40 vol.% BR demonstrated a flexural strength of 15.5 MPa. Overall, BR–UPR composites showed excellent compatibility with promising mechanical properties as potential insulating construction materials.
... W m·K ) [37], cork-gypsum (0.120-0.190 W m·K ) [38], cement/hemp shives (0.110 W m·K ) [39], and concrete/coconut (0.170 W m·K ) [40]. ...
... ) [39], and concrete/coconut (0.170 . ) [40]. ...
Article
Full-text available
In this work, the effect of alkaline treatment on the thermal insulation and mechanical properties of date palm wood fibers (DPWF) and polylactic acid (PLA) green composite was studied. Alkaline treatment was applied to DPWF using two different solutions: sodium hydroxide (NaOH) and potassium hydroxide (KOH), with concentration of 2 vol.%. The fibers were later incorporated into PLA with weight percentages from 10 to 40 wt.%, to form three composite types: PLA with untreated fibers (PLA-UTDPWF), PLA with KOH treated fibers (PLA-KOH), and PLA with NaOH treated fibers (PLA-NaOH). The prepared composites were for use as a green thermal insulation material. The composites were tested to assess the effect of treatment on their physical (density and degree of crystallization), thermal (thermal conductivity, specific heat capacity, thermal diffusivity, thermal degradation, glass transition, and melting temperature), and mechanical properties. Moreover, the composite structural characteristics were investigated using FTIR and SEM analysis. The alkaline treatment significantly increased the crystallinity of the composites, specifically for higher filler loadings of 30 and 40 wt.%. The crystallinity for the 40 wt.% increased from 33.2% for PLA-UTDPWF, to 41% and 51%, for PLA-NaOH and PLA-KOH, respectively. Moreover, the alkaline treatment reduced the density and produced lighter composites than the untreated specimens. For instance, the density of 40 wt.% composite was reduced from 1.43, to 1.22 and 1.30 gcm3 for PLA-NaOH and PLA-KOH, respectively.
... The developed UPR-PUD composites attained higher compressive strength than that of other UPR-based composites such as UPR-rubber [24] and UPR-date seed [32], and were comparable with the compressive strength of UPR-bauxite residue composite [25] and UPR-calcined kaolin clay [38], with an advantage for the current composites in that they have a lower density. Furthermore, the proposed UPR-PUD composites achieved greater compressive strength than several lightweight insulation materials, with a compressive strength ranging from 2.4 to 3.3 MPa [39], as well as mineral wool and sisal fiber-reinforced building materials, with a strength of 3-4.5 MPa [40]. The average tensile characteristics of the UPR-PUD composites for various filler loadings are shown in Figure 11. ...
... MPa) [32] and UPR-bauxite residue (4.0-19.3 MPa) [25], and are very close to the tensile strength of UPR-red shale [41], UPR-carbon nanotubegraphene (26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42) [42], UPR-non-metallic fractions (28)(29)(30)(31)(32)(33)(34)(35)(36) [43], and UPR-jute (37-43 MPa) [44] ...
Article
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The massive production of Polyurethane foam from various products generates an extensive amount of waste, mostly in the form of dust that is emitted while cutting, trimming, or grinding the foam. In this research, the polyurethane dust (PUD) waste is incorporated into unsaturated polyester resin (UPR) to fabricate a heat insulation composite material to be used in construction. Filler percentages ranging from 10% to 50% were used to make the UPR-PUD composite materials. The thermal and mechanical properties of the material were studied in order to evaluate the ability of the composites for this type of application. Thermogravimetric Analysis and Differential Scanning Calorimeter tests were applied to determine the thermal stability of the material. In addition, the microstructure of the prepared composites and the incorporation of PUD filler into the polyester matrix were investigated by Scanning Electron Microscopy, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) analysis. The FTIR and XRD analyses suggested that adding PUD improved the curing process of unsaturated polyester and enhanced its crystalline structure. The experimental results showed promising thermal insulation capability, with low thermal conductivity in the range of 0.076 to 0.10 and low water retention. Moreover, the composites exhibited compression strength between 56 and 100 MPa and tensile strength between 10.3 and 28 MPa, much higher than traditional thermal insulators and many building materials.
... W/mK) was shown for natural hydraulic lime containing either hemp shives or hemp shives and fibers [23]. Ground rice husks, spelled bran, and Khorasan wheat chaff investigated in the present paper had thermal properties that agreed with natural-fiberreinforced mortars [3,4,[24][25][26]. Palm oil fly ash in the replacement of cement (up to 10%) and oil palm fibers as additive (0-1.5 wt %) in a sustainable mortar involve a reduction of about 40% in thermal conductivity with respect to conventional mortar matrix [24]. ...
... and 0.35-0.8 W/mK was achieved with 10% of coconut and durian, respectively [4]. However, the increased amount of fibers resulted in a lower mechanical performance, even if within the standard recommended range for mixture in most cases. ...
Article
Full-text available
This paper investigates the influence of adding vegetal fibers on thermal and acoustic performance based on natural hydraulic lime. Mortar samples with 10% weight of vegetal fibers were fabricated adding water to obtain easily workable mortars with good consistency; their performance was compared to mortar samples without vegetal fibers. The fibers were of different types (rice husk, spelt bran, and Khorasan (turanicum) wheat chaff) and size (as-found and ground form). Thermal performance was measured with the Small Hot Box experimental apparatus. Thermal conductivity was reduced in the 1–11% range (with Khorasan wheat chaff and rice husk); no significant reduction was found with spelled bran in the mixture. When ground, fibers were characterized by both good thermal and acoustic absorption performance; a reduction of 6–22% in thermal conductivity λ was achieved with spelled bran (λ = 0.64 W/mK) and rice husks (λ = 0.53 W/mK), whereas the Khorasan wheat chaff had the highest sound absorption average index (0.38). However, the addition of fibers reduced sound insulation properties due to their low weight densities. This reduction was limited for rice husks (transmission loss value was only 2 dB lower than the reference).
... This small conductivity value was indubitably engendered by the higher volume of voids created by the addition of DPWA into the CEB mixture. Therefore, the larger the void ratio, the lower the thermal conductivity of the specimen (Khedari et al. 2001). Note that these voids are generally filled with air (Boumhaout et al. 2017), which means that the thermal conductivity progressively diminishes as the volume of air in voids goes up as a result of the increasing amount of DPWA within the mixture. ...
Article
This paper presents an experimental investigation to examine the mechanical, thermal, and physical properties, and to perform the microstructural analysis of compressed earth block (CEB) incorporating date palm waste aggregates (DPWA) as a thermal insulating material and stabilized with quicklime. The findings indicated a quite high improvement in the thermal insulation performance of blocks integrating date palm waste aggregates (DPWAs). It was also found that the compressive and flexural strength values of CEB dropped when the DPWA content increased while still remaining within the interval advocated for compressed earth blocks (CEBs). In addition, the CEB elastic modulus followed the same pattern as the flexural and compressive strengths. The scanning electron microscope (SEM) observations and the EDX findings came to corroborate all the results related to the mechanical and thermal properties of CEBs.
... This conclusion is in the line of the observations already made in a series of studies [Munawar 2007;Tran 2015;Yan 2016;Ezekiel 2011;Oda 2012;Ramli 2013]. Khedari et al. [Khedari 2001] studied the effect of fibre length and fibre content on compressive strength of specimen. The composite specimen was produced using 1:1:1.5 proportion (cement: sand: water by mass) mortar reinforced in the range of 10-30% of coconut fibre by mass of cement. ...
Conference Paper
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A research work program is undertaken to promote the use of green materials in civil engineering as a good solution to reduce the negative effects on the environment. Natural fibres are known as green alternatives for building materials. In present study, the impact of the mass of fibre on the mechanical properties of coconut fibre-reinforced mortar is investigated. The experiments in both fresh and hardened states of mortars were conducted in accordance with EN standards. Samples without fibre and with 1, 2, 3 vol.% fibres were cast and cured for 7, 14, 28 days. The results in hardened state of mortar indicated that the addition of fibres can reduce the compressive strength but increase the flexural strength of mortar in comparison with the mortar without fibre. The increase of water absorption capacity with the fibre content increase was also recorded with the increase of fibre content. Mortar incorporating 2% coconut fibres with 1.5 cm average length has the best mechanical properties. Moreover, a remarkable decrease of the workability of mortar incorporating coconut fibres was observed. However, the quantity of heat emitted in accordance with the development of the temperature of samples of freshly made mortars is decreased with the increased of fibre content.
... The reduction in compressive strength can also be attributed to the congestion or balling of the fibers which weaken the bond between the fibers and the matrix. Khedari et al. [65] related the reduction in compressive strength of fiber-reinforced cementitious materials to the low density of the specimens. Hence, specimens containing flexible fibers are expected to have a lower density as compared to an unreinforced specimen since these fibers induce more voids, which reduces the mass of the material [66]. ...
Article
Full-text available
Fiber reinforced mortars (FRM) are growingly used in several fields of building technology (e.g., façade panels, roofing, raised floors and masonry structures) as building elements. One of the promising type of fiber for these composite materials can be textile waste originated from cloth wastes. The use of this sort of recycled materials and wastes as cement reinforcement within the building sector can play a relevant role in sustainability, both the environmental, economic and social perspectives. In this paper, the design mechanical properties (flexural and compressive strengths at 7, 28 and 56 days as well as toughness and stiffness) together with durability properties of cement pastes reinforced with short Textile Waste Fiber (TWF) in contents ranging from 6 to 10 % by weight fraction cement was investigated. The results were compared with those obtained from Kraft Pulp pine Fiber (KPF), taken as reference. The main conclusion is the feasibility of using this type of fiber as potential reinforcement in construction materials with the optimum dosage of 8%. Although the flexural resistance and toughness of the TWF composite are lower than KPF control by almost 9%, the compressive strength and stiffness together with durability properties have proven to be enhanced respect to the reference composite.
... The decrease in the thermal conductivity of the blocks can be associated with the introduction of air voids into the composites which results in a decrease in the density. A similar study also showed that shorter coconut coir exhibited lower thermal conductivity compared to the longer ones due to the higher introduction of voids in the composites (Khedari et al., 2001). ...
Article
Full-text available
The high energy consumption by buildings has called for a need to use energy-efficient material for future construction applications. Cementitious composites in various forms are the most used building material for the construction of buildings. Therefore, in order to ensure these buildings made with cementitious composites are energy-efficient, it is imperative to find innovative and sustainable ways to improve the thermal properties of these cementitious composites. One of the sustainable and effective ways to improve the thermal properties of cementitious composites is with the incorporation of various waste. Therefore, this paper aims to discuss different types of wastes that can be recycled into cementitious composites to improve the thermal properties (i.e. reduce thermal conductivity) based on existing experimental studies. Discussion from this paper showed that recycled materials such as rubber and plastics can be used to reduce the thermal conductivity of cementitious composites when used as a replacement of up to 50% of natural aggregates. It was also concluded that there is a good relationship between density and thermal conductivity of cementitious composites and waste/recycled materials can be incorporated as aggregate/filler in cementitious composites to improve the thermal performance. However, there is a need for the limitations associated with the use of these waste/recycled materials to be resolved before they are incorporated into cementitious composites.
... wt% and a moisture content of 6-7 wt%. Jongjit Hirunlabh et al. [15] introduced new lightweight composite construction materials with low thermal conductivity using coconut and durian as raw materials. The experimental investigation reveals that the addition of these fibres reduces the thermal conductivity to a lower value of about 0.2543 W/mK. ...
Article
Full-text available
Due to the limited supply of natural resources, rapid urbanization causes a scarcity of traditional building materials. On the other hand, the energy consumed by conventional building materials is polluting the air, water, and land. There is a need to implement cost-effective, environmentally friendly technology and update traditional techniques with accessible local materials to meet the ever-increasing demand for energy-efficient building materials. Agro-industrial and other solid waste disposal is another serious issue of concern in developing countries. At the same time, invasive aquatic weeds like water hyacinth (WH) are posing severe economic and environmental issues in India. At present agro wastes are used as a raw material for bio thermal insulation materials. This paper reviews a practical proposal for utilization of WH as a thermal insulation material. The various methodologies to design the water hyacinth cement composite panel and different physical, thermal properties are discussed in the current review. Water hyacinth based thermal insulation materials is evaluated for their methods of production and physic-thermal properties and compared with agro-waste based thermal insulation materials. The use of WH in the construction industry would contribute to a cleaner environment. In brief, it can be stated that self-supporting WHP-cement boards could be used as an alternative to thermal insulation material. This material increases the energy efficiency of building in areas where WH is a chronic problem.
... The thermal conductivity of porous materials is governed by the voids presents in samples. These voids are occurring from fibers packing [40]. More the porosity rate increases, more the conductivity values decreases and more the density of the composite increases, more the conductivity values increases. ...
Article
This work is dealing with the use of miscanthus, recycled textile and rice husks as reinforcement for chitosan matrix to elaborate new insulating composites for building application. Insulating composites having thermal conductivity of 0.07–0.09 W.m⁻¹.K⁻¹ and density of 350–400 Kg.m⁻³ were manufactured by thermocompression. Different granulometry of miscanthus (0.2–0.5 cm and 1–2 cm) and rice husks (1–2 cm) have been used with and without textile to evaluate the effect of reinforcements particle size and nature on composites thermal and mechanical properties. Thermal conductivity and effusivity shows a linear behavior related to their increasing by raising up the reinforcement’s particle size. The highest mechanical properties in bending (modulus: 69–65 MPa; stress: 0.48–0.45 MPa) and compression (modulus: 36–26 MPa; stress: 0.65–0.56 MPa) were found for the formulations with small size miscanthus. Thus, the incorporation of small miscanthus particle size <1 mm leads to satisfying and promising results in terms of composites competing with the conventional insulating materials used nowadays.
... En particulier, la structure conditionne la répartition de l'eau au sein du matériau, l'eau se trouvant majoritairement dans les petits pores (Boutin, 1996). C1-H et HB-S présentent tous deux des résultats proches de ceux d'autres bétons de chanvre et de moelle de tournesol issus de la littérature, et leurs valeurs de conductivité thermique sont inférieures à 170 et 80 mW/(m•K), respectivement, dans toute la gamme d'humidité relative, ce qui représente un bon comportement isolant par rapport à d'autres matériaux de construction, traditionnels (Breuer et al., 2020;Côté & Konrad, 2005) et biosourcés (Haba et al., 2017;Khedari et al., 2001). ...
Thesis
In France, thermal regulations for buildings are changing to face the climatic challenges. The “Grenelle 2” law and the “Plan de Rénovation Energétique de l'Habitat” strategy establish requirements that motivate the search for innovative solutions for the insulation of buildings with high thermal losses. This is the case of national heritage, whose bio-energy retrofit is at the heart of this thesis project. In this context, the agroconcrete industry is currently experiencing an upturn driven by the economic and environmental benefits of the exploitation of agricultural waste and of the local production of resources. This work seeks to characterize lime-based concretes made from sunflower pith and maize pith, two agricultural by-products available in large quantities and whose properties have been scarcely studied. To this end, a study of the mechanical, hygrothermal and acoustical characteristics, compared to the properties of hemp concrete, is carried out, focusing on the impact of the binder-aggregate couples. This experimental campaign has the double objective of exploring new methods of characterization of macroscopic properties. In addition, a mathematical model, which considers the coupling of thermal and hygroscopic effects, is proposed in order to describe the hygrothermal response of the concretes studied at the wall scale. The experimental study has corroborated that lightweight pith concretes show relatively low mechanic characteristics, which place them in the limit of the threshold for “wall”-type applications according to the “Règles Professionnelles Construire en Chanvre” guideline. However, its interesting hygrothermal properties, whose variation with humidity was determined, make it suitable for use as interior insulation, which is the main application envisioned by the project. The campaign also highlighted the extent of the impact of the interactions between the pith and the binder on the properties and the importance of studying the compatibility between aggregates and binders when developing new concretes. During this campaign, a new device for measuring the thermal conductivity of walls was conceived. The cross study of the properties resulted in a contribution to the determination of thermal conductivity and water vapour permeability from acoustic measurements. On the other hand, the results of the numerical study underline the influence of climate on the response of the wall, which determines the choice of the insulating material, and revealed that the presence of pith does not guarantee a greater degree of hygroscopicity of the concrete than the presence of hemp shiv. This hygroscopicity has been proven to have a significant impact on surface heat flows. Lastly, the proposed numerical model is used to quantify the impact of the presence of several kinds of thermal flowmeters on the heat flow passing through a wall during a laboratory test under controlled hygrothermal solicitations.
... Natural fibers can be of any shape and size available for construction purposes (Scheele and Harris 1998). Numerous studies on using natural fibers and agricultural wastes as an admixture in various forms after treating are available to create composite construction materials (Khedari et al. 2001;Ghavami, Toledo Filho, and Barbosa 1999;Venkatarama Reddy et al. 1998). The inclusion of natural fibers in the earthen materials tends to improve the ductile property and reduce cracks (Ghavami, Toledo Filho, and Barbosa 1999;Millogo et al. 2014;Segetin, Jayaraman, and Xu 2007). ...
Article
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Earth has been used as a material for the building in the form of red bricks, sand mortar, mud floors, and lime sand ceiling since the earlier civilization of mankind. Due to its numerous climatic changes and the lack of standards, the earth’s use is decreased. Due to potential capacity and less energy consumption in producing compressed earth blocks exhibits more promising structures than other earth materials. This review article illustrates that using compressed earth blocks with natural fibers will be an excellent alternative for conventional materials. Also, the paper discusses the thermal comfort exerted by naturally available materials such as banana fiber, coconut fiber, sisal fiber, palm fiber, and cassava peels. Natural fibers also increase the mechanical behavior such as compressive, tensile, and water absorption capability of these blocks, which is environmentally friendly and exhibits better thermal stability. This study aims to design an earth-building material with a minimum environmental impact and more stability.
... The improvements in this area are being supported by research into new systems of managing waste in a more sustainable way [10]. These facts indicate that numerous research studies have been required over the last few years and are currently being implemented to find out new ways of producing more efficient and modern construction materials [10][11][12]. Applications of concrete, wood and rubber materials in machine foundations have extensively been discussed in the literature recently. ...
Article
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This paper investigates the mechanical properties of two different types of recycled concrete, which use wood and rubber, relative to those characteristics of pure concrete, in terms of maximum load and natural frequencies. This paper contributes to the state of the art in this area in a number of ways. Firstly, the paper provides furtherance to the progressively growing literature in the field of recycled concrete and mechanical properties of materials. Secondly, the paper investigates the mechanical properties of two different types of recycled concrete by means of investigating the natural frequency of the samples, which is a new contribution. Lastly, the results from predicting the natural frequencies of concrete using fuzzy logic have been effectively assessed and compared with the analytical results. Results from the study show that the pure concrete samples produced maximum natural frequency, then concrete samples with wood, and lastly, concrete samples with rubber. The tolerance between the lab test results and fuzzy logic is approximately 5%. These results could have significant implications for furthering recycled concrete research and for designing machine foundations. Evidence of the applicability of fuzzy logic as a predictive and analysis tool for the mechanical properties of recycled concrete are discussed.
... The results revealed that the thermal conductivity decrease with increasing the percentage of cellulose pulp in the earth-based materials. Similar behaviour has been reported in other publications in which the authors used different types of lignocellulosic fibre (Bentchikou et al., 2012;Khedari et al., 2001). The observed reduction of thermal conductivity comparatively to unreinforced composite was found to be 26.43 %, 28.66 %, and 33.13 %, respectively for 5, 7.5, and 10% content of bamboo organosolv reinforced clayey soil matrix, whereas in the composite reinforced with recycled carton pulp the reduction was found to be 21.09 ...
Thesis
Due to the growing concern of deforestation, renewable materials such as recycled cellulosic waste and non-wood fibres provide an alternative solution for partial replacement of wood resources as a reinforcement agent in building blocks. This study consists of exploring the feasibility of producing cellulose pulp and nanofibrillated cellulose (NFC) from plants widespread in Tropical region; raffia fibre (Raphia vinifera), cassava bagasse (Manihot esculenta), ambarella (Spondias dulcis), and bamboo (Bambusa vulgaris); to assess their suitability as a source of reinforcing agent for composites. The recycling process of municipal waste fibres was also studied to promote the conservation of plant resources, as well as the circular economy. Bamboo organosolv pulp (BOP) and recycled waste carton pulp (RWCP) were used as a reinforcement phase in an earth-based matrix at varying fibre contents (0, 5, 7.5, and 10%wt.) to assess their performances and durability for civil engineering construction applications. Fibres were produced using both organosolv and soda methods to assess the effect of processing on fibre properties. The composites were manufactured by the extrusion process and tested after 28 days. The results show that the inclusion of RWCP fibre in the soil matrix significantly improved the performance of the composites compared to matrices reinforced with BOP fibres. Addition of 5 %wt. of RWCP, showed an improvement in flexural strength (56%), specific energy (614%), fracture toughness (57%), wear resistance (48%), and thermal insulation (21%) compared to the control sample. The inclusion of RWCP in earth-based matrix increases the moisture loss, the drying shrinkage and behaves as a water reservoir for earth-based materials. It has been concluded from this study that RWCP has the potential to serve as a suitable reinforcement for the promotion of lightweight earthen wall block materials (reduction of bulk density up to 21% after the inclusion of 10% of RWCP), where flexural strength, ductility, and thermal insulation performance are the primary requirements. Besides, the successful replacement of virgin BOP fibres with RWCP fibres reduces the environmental footprint of the building material. Therefore, the use of this RWCP in the construction industry will be an attractive alternative as it will solve both energy and environmental concerns.
... En particulier, la structure conditionne la répartition de l'eau au sein du matériau, l'eau se trouvant majoritairement dans les petits pores (Boutin, 1996). C1-H et HB-S présentent tous deux des résultats proches de ceux d'autres bétons de chanvre et de moelle de tournesol issus de la littérature, et leurs valeurs de conductivité thermique sont inférieures à 170 et 80 mW/(m•K), respectivement, dans toute la gamme d'humidité relative, ce qui représente un bon comportement isolant par rapport à d'autres matériaux de construction, traditionnels (Breuer et al., 2020;Côté & Konrad, 2005) et biosourcés (Haba et al., 2017;Khedari et al., 2001). ...
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En France, la réglementation thermique pour les bâtiments évolue pour faire face aux enjeux climatiques. La loi Grenelle 2 et le Plan de Rénovation Energétique de l’Habitat établissent des exigences qui motivent la recherche de solutions novatrices pour l’isolation de bâtiments à fortes déperditions thermiques. C’est le cas du patrimoine vernaculaire, dont la bio-rénovation énergétique est au coeur de ce projet de thèse. Dans ce contexte, la filière des agro-bétons connaît actuellement un essor poussé par les avantages économiques et environnementaux de l’exploitation de déchets agricoles et de la production locale de ressources. Ce travail cherche à caractériser des bétons à base de chaux et de moelle de tournesol et de maïs, deux sous-produits agricoles disponibles en grande quantité et dont les propriétés ont été peu étudiées. A cette fin, une étude des caractéristiques mécaniques, hygrothermiques et acoustiques, comparées aux propriétés du béton de chanvre, est menée, en mettant l’accent sur l’impact des couples liant-granulat. Cette campagne expérimentale a le double objectif d’explorer de nouvelles méthodes de caractérisation des propriétés macroscopiques. En outre, un modèle mathématique, qui prend en considération le couplage des effets thermiques et hygroscopiques, est proposé afin de décrire la réponse hygrothermique des bétons étudiés à l’échelle paroi. L’étude expérimentale a permis de constater que les bétons de moelle à faible densité présentent des caractéristiques mécaniques relativement faibles, les classant à la limite du seuil pour les applications de type « mur » des Règles Professionnelles Construire en Chanvre. Toutefois, ses propriétés hygrothermiques intéressantes, dont la variation avec l’humidité a été déterminée, le rendent apte à l’utilisation en tant qu’isolant intérieur, qui est l’application principale envisagée par le projet. La campagne a également mis en évidence l’ampleur de l’impact des interactions entre la moelle et le liant sur les propriétés et l’importance d’étudier la compatibilité entre agrégats et liants lors du développement de nouveaux bétons. Lors de cette campagne, un nouveau dispositif de mesure de la conductivité thermique des parois a été mis en place. L’étude croisée des propriétés a débouché en une contribution à la détermination de la conductivité thermique et de la perméabilité à la vapeur à partir de mesures acoustiques. D’autre part, les résultats de l’étude numérique soulignent l’influence du climat sur la réponse de la paroi, qui détermine le choix du matériau isolant, et ont révélé que la présence de moelle ne garantit pas un degré d’hygroscopicité du béton plus important que la présence de chènevotte. Cette hygroscopicité a été prouvée avoir un impact non négligeable sur les flux thermiques en surface. Enfin, le modèle numérique proposé est utilisé pour quantifier l’impact de la présence de différents types de fluxmètres sur le flux thermique traversant une paroi lors d’un essai au laboratoire sous des sollicitations hygrothermiques maîtrisées.
... In particular, the microstructure conditions the distribution of water within the material, the water being mainly found in the small pores (Boutin, 1996). Nevertheless, all hemp and pith composites from the present study show thermal conductivity values below 180 W/(m•K) throughout the saturation range, which stands for a good insulating performance compared to other building materials, both traditional (Breuer et al., 2020;Côté and Konrad, 2005) and bio-based (Haba et al., 2017;Khedari et al., 2001). ...
Article
This paper deals with the experimental assessment of the influence of water content on thermal conductivity, thermal effusivity, heat capacity and vapor permeability of pith and hemp shiv composites. The results, which will be used to enrich modelling databases, show that all four properties increase their value with relative humidity , especially for pith composites, while remaining within adequate margins. They are compared to the results commonly measured for other porous construction materials, namely hemp concrete, wood, and rammed earth. This comparison allows to better understand the influence of the material morphology and nature on hygrothermal properties in presence of moisture. It has been noted that, in hygroscopic conditions, the specific heat cannot always be deduced from the specific heat of water and of the dry material due to the interactions between the adsorbed water and the material. On the other hand, the transport of liquid water has been observed to play a significant role in the hygroscopic transfers.
... Based on that study, the thermal conductivity of the cement composite varied between 0.650 and 0.840. Further, other studies (Khedari et al., 2001;Lertwattanaruk and Suntijitto, 2015) similarly proved that the addition of vegetal and natural fibers to the cement-based materials could enhance the thermal performance with respect to the control sample by 40-80%, depending on the fiber type and volume. Increasing the fiber quantity in the material, generally, leads to higher porosity which, in turn, may decrease the thermal conductivity, thereby better thermal insulation (Quintaliani et al., 2022). ...
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Within the building construction sector, fiber cement boards have attracted interest as facade cladding materials in the last ten years, especially those that incorporate-for reinforcing purposes-natural and/or recycled synthetic fibers (i.e, from the textile industry). So far, the design-governing parameters of facade cladding panels have been mechanical strength, durability, constructability, aesthetics, insulation capacity, and fire resistance. From the sustainability perspective, the impact of the facade on the economic and energy efficiency performance is most often the parameter that leads the decision-making process. Within this context, the quantification of the sustainability performance of the facade-accounting for economic, environmental, and social indicators-is unfrequently carried out in design and project phases, this being attributed to the lack of methodologies that allow considering and quantifying some relevant indicators representative of the facade sustainability performance. As consequence, decisions made based on solely economic and on some of the environmental indicators might lead to solutions with lower sustainability performance than that required (or expected). Recycled textile waste fabric-reinforced cement board as a facade-cladding material for building envelopes is the focus of this research. In order to characterize the fire resistance, and thermal and acoustic insulation-as relevant service-ability parameters-of this material, an experimental program was carried out. Likewise, the sustainability performance of this facade-cladding is assessed through a method based on the Integrated Value Model for Sustainability Assessment (MIVES). This multi-criteria decision making (MCDM) model relies on the value function concept and the multidisciplinary participation of experts to identify and quantify the relevant indicators of the facade sustainability performance and the relative importance of indicators and requirements. The MIVES-based model generated for this research can be straightforwardly used for assessing the sustainability performance of facade-cladding techniques made of any material and for any type of building (and location). The application of the MIVES model led to the sustainability index of this new material for facade-cladding ranging from 0.68 to 0.71 (/1.00) for different weighting scenarios.
... However, for larger DPF inclusions (more than 15%), these effects become negligible. This is due to the difficulty of aligning and packing the shorter fibers as compared to the larger ones [51]. ...
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Since cork has low density, low thermal conductivity, and water resistance, mixing cork with mortar can effectively improve the thermal and moisture insulation of mortar materials. In this study, cement-cork mortars with different cork volume admixtures was prepared. The fresh state consistency and compressive strength of cement-cork mortars were studied. The porosity and pore distribution characteristics of the prepared samples were obtained using microparticle mercury porosimeter. The thermo-physical parameters (thermal conductivity, specific heat, heat storage coefficient, and thermal diffusivity) and hygric properties (isothermal adsorption curve, liquid water diffusion coefficient, and water vapor permeability) of cement-cork mortars were studied experimentally. Meanwhile, The variation of thermo-physical parameters of the prepared samples with temperature (within the range of 20–70 °C) and moisture content (with the relative humidity range of 0–100%) were obtained. The results show that the hygro-thermal parameters of cement-cork mortars decreased with the increase of cork content (the largest decrease in thermal conductivity was 52.6%, whereas the drop in liquid water diffusion coefficient was 87.9%). Furthermore, temperature and moisture content had great influence on the thermo-physical parameters of the samples (the maximum growth rates of thermal conductivity and specific heat within the studied temperature range were 7.5% and 27.3%, respectively, whereas the corresponding values within the studied range of moisture content were 60.7% and 26.7%, respectively).
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Coconut-coir, a natural fiber, strong and lightweight, abundantly in India and Vietnam, can be an excellent choice to produce polymer composites. Due to the higher specific modulus and durability, these composites have a myriad of applications. This article provides a novel experimental research study on the fabrication and investigation of mechanical as well as thermal behavior of coir fiber/woven-carbon fiber/epoxy resin hybrid composite. The composite samples were formulated with distinct fiber weight percentages viz. 30%, 20%, and 10% using the vacuum bagging technique. Mechanical behavior (tensile, compressive, flexural, and impact strength) and thermal behavior (Thermogravimetric analysis) of coir fiber/carbon fiber/epoxy resin hybrid composites were studied according to the ASTM standards. Moreover, Scanning Electron Microscopy (SEM) was performed to examine the morphological characterization of tensile fractography specimens and analyze the properties of the fiber/matrix bonding of the surface before and after alkaline treatment. The treated fiber shows good matrix binding and less fiber pull-out as compared with untreated fibers. The result also revealed that the hybrid composite has more robust properties under mechanical loading than single fiber-reinforced composite.
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Natural fibers are increasingly used in composites because of their low cost and good mechanical properties. Cement reinforced with natural fibersis contemplates as a new generation of construction materials with superior mechanical and thermal performance. This study of three sizes’effect of Doum palm fiber explores the mortar’s behavior reinforced with different fiber ratio. The aim is to determine the optimal addition to improve mechanical and thermal properties of natural fiber reinforced cements. Physical, mechanical and thermal properties of composite are examined. Tensile properties of Doum fibers are verified to determine their potential as reinforced material. Findings prove that the use of alkali-treated Doum fiber as reinforcement in cement mortar composite leads to the upgrading of the mechanical properties including thermo-physical properties against composites reinforced with raw fibers and control cement mortars. While, the compression and flexural strength of the cement mortar reinforced with alkali-treated Doum fiber with diameter 0.3 mm (CT3) are metered to be 11.11 MPa, 5.22 MPa, respectively for fiber content 0.5%. Additionally, based on thermo-physical tests, it is assessed that the thermal conductivity and diffusivity decrease for cement mortar reinforced with Doum fiber with diameter 0.2 mm (CT2)
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This paper deals with the investigation carried out to study the Strength Properties of Papercrete Building Bricks and these results were compared with conventional bricks. The papercrete brick did not fully collapse even at ultimate load and it never failed catastrophically. Hence the outer faces got cracked and peeled out. From the observation of the compression test, it is inferred that the papercrete bricks are having less elastic and are less brittle. Water absorption test was carried out as per the guidelines given in ASTM C-642. After coated with an external coating agent, the percentage of water absorption of the papercrete bricks was nearly the same as the conventional bricks. Also young’s modulus and poisson’s ratio of coated papercrete bricks was determined.
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This study aims to investigate the possibility of recycling devulcanized rubber tires for their use as fillers for thermoplastic thermal insulators. A devulcanized rubber tire was ground into powder and then mixed with polystyrene in different proportions (0–50 wt%) using a melt extruder. The mixture was then transferred to a hot press for fabricating the final sample. The effect of devulcanized rubber tire content on the physical, thermal, and mechanical properties of devulcanized rubber tire–polystyrene composites was investigated. Thermal conductivity measurements were verified using series and parallel conduction models and the Hashin and Shtrikman model. Composites with less than 40 wt% devulcanized rubber tire content exhibited superior properties, with thermal conductivity ranging from 0.0502 to 0.07084 W/(m⋅K), density from 462.8 to 482.32 kg/m³, compressive strength from 11.66 to 7.47 MPa, and flexural strength from 40.4 to 19.26 MPa. Moreover, alkaline treatment of the devulcanized rubber tire further improved the mechanical properties and thermal stability of the composite. The results are supported by characterization techniques such as scanning electron microscopy, thermogravimetric analysis, and Fourier-transform infrared spectroscopy. The chemical treatment was found to enhance the coherence between treated devulcanized rubber tire and polystyrene. The novel devulcanized rubber tire–polystyrene composite can be used as an alternative insulation material because of its superior properties compared with those of conventional insulation materials. Furthermore, the environmental and economic implications of using devulcanized rubber tire–polystyrene composites as a new insulation material are discussed herein.
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Due to respect for the environment and the search for more sustainable materials, scientists have started in recent decades to launch studies on bio-composite materials. It is well known that building materials are among the most commonly used materials and have an obvious negative impact on the environment. The development of environmentally friendly composites as insulating materials in buildings offers practical solutions to reduce energy consumption. Therefore, this work presents the use of a new bio-composite material composed of natural fibers, date palm fibers, cement, and sand. In addition, the study on the effect of adding date palm fibers on the thermo-mechanical characteristics of mortars assesses the thermal insulation properties as well as the water absorption and mechanical performance of this new bio-composite material to use it in the construction of buildings. The percentage by weight of date palm fiber in the test samples varied from 0% to 30% for a fiber size of length equal to 7 mm. The characteristics of these samples were determined experimentally in terms of resistance to bending and compression as well as thermal conductivity. The results show that while increasing the weight of date palm fiber, an obviously reduction in thermal conductivity, flexural, and compressive strength of the composite is observed. Hence, date palm fiber has a positive effect on the thermo-mechanical properties of the composite material. Therefore, it considerably improves the insulating capacity of the mortar.
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The constant increase in environmental pollution and consumption of energy has prompted the construction industry to focus on thermal insulation. Non-renewable resources are commonly used for the production of thermal insulation materials. Therefore, a number of issues arise relating to the reuse or recycle of such materials. Also, a huge amount of energy is required for their production. Yet, another major issue of concern in India is the aquatic weed infestation in water bodies. Invasive weeds such as water hyacinth (WH) are posing severe environmental as well as economic issues. A potential remedy for these waste disposal and high dependence on non-renewable materials are the conversions of these aquatic weeds into sustainable construction material. The primary objective of this paper is to explore the utilization of WH petioles as a raw material resource for the production of thermal insulation material. The methodology to design the water hyacinth cement composite panel and its properties such as bulk density, water absorption, thermal conductivity, and flexural strength are included in this paper. The WH was collected; petioles were separated, sun-dried, milled into smaller particle sizes, and blend with a homogenous paste of cement and water. The homogenous mixture was poured into a mould and was compacted to produce the thermal insulation boards. The panel boards were made with water hyacinth particles that pass through 2.36 mm sieve. Water to water hyacinth ratio (w: WH) and the water hyacinth-cement ratio (WH: cement) used in the present work are 1.75 and 60: 40 respectively. In this paper, a comparative study between the thermal insulation materials made from WH with agro-waste based panel board and conventional thermal insulation materials are also included. This study indicates that WH biomass resources are a very good candidate for developing thermal insulation material and the correct combination of WH is absolutely comparable with conventional materials.
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The main objective of this paper is the improvement of the thermal properties of gypsum plaster through mixing it with chicken feather waste, in order to be used in walls and ceiling mortars. The thermal conductivity, thermal diffusivity, and thermal effusivity of the studied samples were measured using the steady hot plate, the flash, and the transient hot plate methods, respectively. The obtained results show that the increase in the mass fraction of chicken feathers resulted in a significant improvement consisting of a reduction of the material thermal properties. This reduction was up to 36% for the thermal conductivity, 13% for the thermal diffusivity, 23% for the thermal effusivity, and 16% for volumetric thermal capacity. These results were employed to perform dynamic thermal simulations on a typical residential building using the Design Builder software. Results showed that the incorporation of the composite material with 5% of chicken feathers waste mass fraction in the external walls and the roof of the studied building decreased the cooling consumption in summer by 24,8 % and the heating requirement in winter by 29,40% and considerably reduced the CO2 emissions by approximately 408 kg per unit area.
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This article focuses on the investigation of properties of Phoenix sp. fiber based geopolymer composites. Control samples (0 wt.%) and fiber reinforced samples (1, 2, 3, and 4 wt.%) with different quantities were produced and determined their physical, mechanical, morphological, ultrasonic pulse velocity, water absorption, thermal conductivity and fracture toughness properties. The outcomes show that the incorporation of Phoenix sp. fibers to geopolymer improved the splitting tensile (1.28–2.35 MPa), compressive (27.85–32.18 MPa) and flexural strengths (3.34–6.53 MPa). By contrast, as the fiber loading increased to 4 wt.%, the workability and bulk density of geopolymer decreased to 86% and 13%, respectively. Furthermore, a linear relationship was evidenced between the bulk density and thermal conductivity, as well as ultrasonic pulse velocity and compressive strength. Due to the hydrophilic character of Phoenix sp. fibers, the water absorption increased as the fiber content increases. Due to the local mechanisms that control the bridging activity, the addition of Phoenix sp. fibers improved the fracture toughness of the composites.
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In recent decades, scientists have started to search for more sustainable and environmentally friendly materials. It is known that building materials are among the most used materials and have a visible negative effect on the environment. The development of environmentally friendly composites in buildings offers different solutions to decrease energy consumption. The aim of the present study is to investigate a new biocomposite material fabricated with natural date palm fibers (DPFs), cement, and sand. The main objective is to assess the thermal insulation characteristics as well as the water absorption and mechanical performance of this material for building industry. The percentage by weight of DPF in the studied specimens ranged from 0% to 30% for two fiber sizes. The characteristics of these specimens were determined experimentally in terms of flexural and compression strength as well as thermal conductivity. The results confirmed that the thermal conductivity decreases with the addition of DPF. Also, the compressive strength of the composite decreases with the weight reduction. Thus, DPF has a positive effect on the thermo-mechanical properties of the considered material. Consequently, it considerably improves the mortar insulating capacity.
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Due to the growing concerns of deforestation, renewable materials as recycled cellulosic waste and non-wood fibres provide an alternative solution for partial replacement of wood resources as a reinforcement agent in building material. This study examined the effect of cellulose pulp inclusion on the physical, mechanical, and thermal performance of extruded cement stabilized earth-based matrices. Laboratory experiments of earth-based matrices reinforced with two types of fibres (bamboo pulp and recycled waste carton pulp) at varying fibre contents (0, 5, 7.5 and 10 %wt.) were performed. The results show that the inclusion of recycled waste carton pulp fibre in the soil matrix significantly improved the performance of the composites compared to matrices reinforced with bamboo pulp fibre. Addition of recycled waste carton pulp displayed improvement in flexural strength (56 %), in toughness (733 %), and in thermal insulation (36.35 %) compared to the control sample. Inclusion of recycled waste carton pulp in earth-based matrix increases the moisture loss, the drying shrinkage and behaves as a water reservoir for earth-based materials. It has been concluded from this study that recycled waste carton pulp has the potential as a suitable reinforcement for the promotion of lightweight earthen wall block materials (reduction of bulk density up to 21 % after the inclusion of 10 % of recycled waste carton pulp), where flexural strength, ductility, and thermal insulation performance are the primary requirements. In addition, the successful replacement of virgin bamboo pulp fibres with recycled waste carton pulp fibres reduces the environmental footprint of the building material. Therefore, the use of this recycled waste carton pulp in the construction industry will be an attractive alternative as it will solve both energy and environmental concerns.
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Because of the restricted gracefully of characteristic assets, quick urbanization causes a shortage of conventional structure materials. Then again, the vitality devoured by customary structure materials is contaminates air, water and land. There is a need to actualize practical, earth amicable innovation and update conventional methods with available neighborhood materials to fulfill the ever-expanding need for vitality proficient structure materials. Agro-mechanical and other strong garbage removal is another major issue of worry in creating nations. Simultaneously, obtrusive amphibian weeds like water hyacinth (WH) are presenting serious financial and ecological issues in India. At present agro squanders are utilized as a crude material for bio warm protection materials. This paper surveys a reasonable proposition for use of WH as a warm protection material. The different techniques to plan the water hyacinth concrete composite board and diverse physical, warm properties are examined in the ebb and flow audit. Water hyacinth based warm protection materials are assessed for their strategies for creation and physic-warm properties and contrasted these and agro-squander based warm protection materials. The utilization of WH in the development business would add to a cleaner situation. To sum things up, it tends to be expressed that self-supporting WHP–concrete sheets could be utilized as an option in contrast to warm protection material. This material expands the vitality proficiency of working in regions where WH is an interminable issue.
Article
In the present work tensile, flexural, impact and hardness properties of Prosopis juliflora bark (PJb), Banana fiber (Bf), and Coconut fiber (Cf) reinforced epoxy hybrid bio composites (untreated and alkali treated) are expressed for the first time. This experimental investigation Bf as a base material, PJb and Cf are filler materials. The weight percentage of Bf has been maintained as constant and the remaining two fiber fillers were varied. The untreated composite specimen shows the great enhancement of tensile attributes, flexural, and compression strength with an increase in coconut fiber loading. The better interlinking capability between the natural fiber composite (NFC) and an epoxy matrix is also responsible for effective resistance competence. Also, strong hydrogen bond formation due to the higher polarity of the epoxy matrix enhanced the flexural properties of the hybrid natural composites. Impact strength of untreated specimen has increased up to 25% wt. of Cf and Bf. Further addition of Cf and Bf showed a negative effect. Moreover, the hardness value of untreated specimens has gradually decreased with an increase in coconut fiber loading. The mechanical attributes of untreated composite specimens were compared with the treated composite specimen. The outcomes of alkali treated composite specimen show higher tensile attributes, flexural, compression, impact strength, and hardness compared with untreated composite specimens. Scanning electron microscope (SEM) observations on the fracture surface of composites showed that the surface modification of the fiber occurred and improved fiber-matrix adhesion. Fourier transform infrared (FTIR) and Atomic force microscopy (AFM) also used to observed the interfacial properties and characterization of natural fiber composites respectively.
Chapter
Considering the governmental emphasis on new environmental regulations, the raising global environmental and ecological awareness, and the scarcity of petroleum-based materials, material scientists and engineers have been exploring new substitutions for materials derived from nonrenewable resources. Biobased fibers have received much attention worldwide for decades, especially as reinforcement in composite materials to replace synthetic fibers because of their ecofriendly nature, sustainability, low cost, reasonably good mechanical properties, and nonabrasive characteristics. These fibers can be obtained directly either from plants or animals. The utilization of biobased fibers in composite materials not only offsets the use of fossil fuels but also reduces greenhouse gas emissions and CO2 footprints. Nevertheless, there are some challenges for incorporating biobased fibers into the polymer matrices, for instance, the poor compatibility between the fibers and matrix, relatively high moisture absorption, inferior fire properties, limited thermal stability, and the lack of consistency of fiber qualities. Therefore understanding the properties of biobased fibers and selecting the suitable fibers for composites is very essential to yield the optimum composite products. This aim of this chapter is to provide a comprehensive review of the foremost appropriate as well as widely used biobased fibers. It presents a summary of the types and sources, structure, compositions, the physical, chemical, and mechanical properties of biobased fibers. The applications of natural fiber reinforced polymer composites will be demonstrated. Finally, the chapter concludes with the recent developments and future trends of biobased fibers and their composites as well as key issues that need to be tacked and addressed.
Chapter
Coconut fibers are one of the natural fibers that can be used as reinforcement in cementitious composites. In this chapter, the influences of coconut fibers on the properties of cementitious composites are discussed. The discussion presented in this chapter indicated that coconut fibers are a sustainable and cheaper alternative that can be utilized as a replacement of the conventional fibers. The findings further showed that the use of coconut fibers is detrimental to the fresh, compressive strength, and permeability properties. However, cementitious composites reinforced with coconut fibers with acceptable performance for various applications can be obtained. On a positive note, the use of coconut fibers in cementitious composites enhance the ductility, tensile properties, flexural properties, and insulation properties of cementitious composites. The reduction in the thermal conductivity and density of cementitious composites with the incorporation of coconut fibers opens a pathway to use these cementitious composites for the construction of various building envelopes.
Article
Designing materials with low thermal conductivity ( κ) is of demand for thermal protection, heat insulation, thermoelectricity, etc. In this paper, based on the state-of-the-art first-principles calculations, we propose a framework of a 1T-sandwich structure for designing materials with low κ. The 1T-sandwich structure is the same as the well-known transition metal dichalcogenide but with light carbon atoms in the middle plane. Using different atoms to fill the outer positions, a few novel two-dimensional materials are constructed as study cases, i.e., Mg 2 C, Janus MgBeC, Be 2 C, and Mo 2 C. With a systematic and comparative study, the κ are calculated to be 3.74, 8.26, 14.80, and 5.13 W/mK, respectively. The consistent values indicate the stable behavior of low κ in the 1T-sandwich structure, being insensitive to the component. Our study would help design advanced functional materials with reliable heat transfer performance for practical applications, which reduces the influence of unavoidable impurities.
Article
Among the major challenges facing the modern era of technological and industrial advancements are pollution and exponentially growing energy consumption. Pollution continues to be a menace affecting different aspects of life such as health, productivity, and comfort. This paper focuses on the elimination or reduction of sound pollution in buildings using cement-based boards made from pretreated coconut coir and oil palm fibers obtained from agricultural residues. The study includes an account of the preparation of fiber cement boards made from Portland cement Type 1, limestone powder, water, sand, and pretreated coconut coir and oil palm fibers at 5, 10, 15, and 20% by weight of powder materials, respectively, and a high-range water reducer in order to make sure that the natural materials would be spread in an even way throughout the specimens. Sound insulation tests were performed as key indicators of the performance of the fiber cement boards. It was found that an increase in the proportion of natural materials resulted in fiber cement boards with decreased density, compressive strength, and flexural strength. Furthermore, in relation to both physical and mechanical performance, the boards incorporating coconut fibers were superior to those incorporating oil palm fibers. With an increased proportion of natural fibers, sound insulation performance tended to improve. The boards prepared with coconut coir and oil palm fibers in this study yielded acceptable physical and mechanical properties and showed promise in relation to providing insulative protection against sound.
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The increasing demand for construction materials along with the challenge of waste management has necessitated the development of sustainable materials utilising wastes properly. Therefore, this research examines the utilisation of various agricultural wastes, such as Eggshell Powder (ESP), Sawdust Powder (SDP) and Coconut Husk Powder (CHP), in the production of unfired clay blocks. Samples were made with various percentages of wastes: 10–50% of dry wt. of clay for ESP and 2.5–10% for SDP and CHP. In this study, the physico-mechanical and durability properties of unfired clay blocks were investigated by conducting density, linear shrinkage, capillary water absorption, flexural strength, compressive strength, ultrasonic pulse velocity test, drip test and water spray test. The tests were carried out in two phases, with the first phase including the individual integration of waste in the mixture and the second phase combining ESP (10–30%) with the optimum SDP (2.5%) and CHP (2.5%). The test results show that when the additives were used individually, the 40% ESP samples performed the best whereas for SDP and CHP 2.5% content showed better performance. Contrarily, the samples' overall characteristics deteriorated when ESP, SDP, and CHP were used together. Nevertheless, all the samples met the strength requirement of the standards and passed the durability tests. The results of this study might be useful in assessing the potential of ESP, SDP and CHP for the production of unfired clay blocks as well as finding a feasible solution to the waste management problem.
Article
Global population growth around the world requires significant infrastructure and building developments. The building and construction industry uses excessive quantities of virgin resources for those developments as well as contributing to the waste generated from the residential and commercial sectors. A contemporary solution is required to reduce these negative environmental impacts. In this study, the mechanical properties of cement composites containing kraft fibres (KFs) derived from waste cardboard was experimentally investigated. KFs and metakaolin (MK) were integrated within concrete samples as a cement substitute material. The compressive, flexural, and tensile strength was determined on three mix designs containing 5% raw KFs, 5% surface modified KFs, and matrix modified concrete specimens. Silica fume (SF) was applied to the fibre walls as fibre modification to lower the alkaline zone around the fibre within the cementitious matrix. 5% MK was used as a partial cement substitute to lower the alkaline level of concrete samples. All KF concrete specimens exhibited lower compressive strength properties. However, MK modified samples exhibited the highest tensile strength of 11 MPa. Fibre modified samples had stronger compressive and tensile strength of 20 and 9 MPa, compared to raw KFs. However, raw KFs exhibited a higher flexural strength of 2.5 MPa. The compressive, tensile, and flexural strength of the control were 25, 10 and 2.6 MPa, respectively. Scanning electron microscopy (SEM) observations demonstrated sufficient SF adhesion on the fibre walls, while the energy dispersive x-ray spectroscopy (EDS) observations showed efficient dispersion of all composite materials.
Article
The unique ability of reactive magnesium oxide cement (RMC) to permanently sequester environmental carbon dioxide (CO2), followed by sufficient strength gain, makes it an attractive material for greener construction. The potential of RMC and its combination with various supplementary materials have been demonstrated for construction by several researchers. In this study, the thermal properties of the RMC-based paste, along with its thermal stability after prolonged and cyclic high-temperature exposure, are reported. The results reveal that, in general, the RMC-based paste samples cured under an ambient environment as well as the ones cured under accelerated carbonation undergo strength gain after cyclic exposure to temperature as high as 300 °C. In terms of thermal properties, the general trend was found to be an increase in the specific heat and a decrease in the thermal conductivity and the thermal diffusivity with increasing temperature for both types of RMC-based paste samples. These results reveal a remarkable ability of the RMC to sustain high temperatures with excellent strength retention making it suitable for high temperature and energy storage applications.
Article
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For the transport of frozen products, it is necessary to preserve their quality and enhance their longevity. It aimed to assess the insulation performance of the composite containing date palm fiber and beet pulp in maintaining low temperature during the transport of frozen products. Therefore, this study investigated the physical, thermal, and mechanical properties of date palm fiber and beet pulp composites for different mass fractions of 0, 2.5, 7.5, and 10%, both as stand-alone and as compounds added to hemihydrate gypsum by using the response surface method to state an optimized system. Results showed that by increasing the fractions of date palm fiber and beet pulp, the density of composite samples reduced from 880.02 kg/m³ to 785 kg/m³; however, water absorption increased significantly (by 101.39%). The highest flexural and compressive strengths of the control were, respectively, 4.6 and 26.67 MPa, whereas the lowest of said strengths were, respectively, 3.5 and 42.91 MPa in samples containing 10% palm fiber and 10% beet pulp. Additionally, for the same fiber ratios, the thermal conductivity of composite samples was reduced by 67% compared to the control sample. After optimization, the best mass ratios for palm fiber and sugar beet bagasse were, respectively, 3.05% and 10%. For these samples, water absorption was 96.69%; flexural and compressive strengths were, respectively, 6.27 and 3.87 MPa; thermal conductivity was 0.51 W/mK; and density was 844.15 kg/m³. These properties show that a composite insulant containing date palm fiber and beet pulp are a good candidate for developing thermal insulants. Practical applications Reducing microbic growth and delaying fat and protein oxidation during the storage can increase the durability of food and agriculture products, particularly different types of meats and dairies. To this end, a safe cold cycle is necessary for proper preservation during transport and storage. Cold transport is the main part of the cold chain required for preserving the quality of freshly frozen degradable products. Therefore, in addition to cold storages and refrigerated transport vehicles, the packages are also important. The goal of this research is the progressing of a natural biocomposite that is used as thermal insulant.
Article
Synthetic wollastonite (SW) has been produced with a special green route being made up of three steps by using industrial marble and quartz wastes. Due to the acicular and fibrous shape, SW has been tried to improve engineering characteristics of cementitious lightweight composite mortar (CLCM). In this experimental study, ecofriendly CLCM was developed with SW as a cement replacement material. Physical and chemical properties of SW were specified with XRF, XRD and SEM analysis. The cement replacement levels were evaluated as 0, 0.5, 1, 2, 5, 10 and 20 %. Setting time, normal consistency, and mineralogical investigation with XRD analysis were investigated on cementitious pastes. Flowability, unit weight, water absorption, flexural and compressive strength, ultrasonic pulse velocity (UPV), and thermal conductivity analysis were carried out on CLCMs. Morphological observations reveal that SW grains were quite finer than cement particles, fibrous and acicular in shape, have a high aspect ratio, and have rough surfaces. Depending on the physical properties of SW, the water requirement of the cementitious paste increased and the setting times were delayed. Similarly, the workability of CLCMs decreased slightly, but a significant improvement was observed in the mechanical properties of the mortars at 2 % and 5 % replacement levels. Also, thermal conductivity of the mortars decreased as the SW replacement level increased. This research verifies the technical feasibility of SW application as a cement replacement in CLCM and may further promote the utilization of waste materials in production of SW.
Article
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Conflicting reports on the predominance of fracture or pull-out of woodpulp fibres from a cement matrix prompted a study of a model system of sisal slivers embedded in cement and protruding from one end of the cement matrix. About 200 such systems were tested under tension in the fibre direction and their load-extension behaviour and modes of failure were recorded. The length of embedment ranged from 10 to 60 mm. The tensile strength of the slivers averaged 420 MPa. The onset of debonding was independent of embedment length. Slivers with a shorter embedment length tended to pull out whereas those with a long embedment tended to fail in tension. The change-over occurred at about 30 mm embedment, an aspect ratio of about 110. However, there was no uniformity of frictional restraint along the fibre and the ‘critical length’ was determined by the probability of the formation of strong anchor points.
Article
The average fiber spacing is calculated from the number of fibers crossing a unit area in an arbitrary cross-section of the composite. This number is a function of the cross-sectional area of the fiber and the fiber concentration and of the type of orientation of the reinforcement. The specific fiber surface is a function of the perimeter and the cross-sectional area of the fiber and of the fiber concentration, but it is independent of the orientation of the reinforcement.
Article
The development of glass fibre reinforced cements and concretes (GRC) has been dependent on effective methods of assessing the strength retention of the alkali resistant glass fibres in a cement environment. The Strand-in-Cement (SIC) Test, described in detail in this paper, has proved to be reliable test method. The glass fibres are tested in a practical commercially available format, in conditions similar to that in a practical cementitious composite. The changes in fibre strength observed in SIC specimens have been shown to relate directly to changes in strength of GRC composites.
Article
The aim of this paper is to determine the characteristics of lightweight insulating concrete using rice husk in the natural state or treated with a 5% lime solution. Reported in the paper are the compressive strength results and the cement contents in each one of the eleven mixes prepared by the substitution of sand and gravel with rice husk. The concretes studied might be defined as materials with hybrid characteristics between lightweight structural concretes and insulating concretes.
Article
This investigation reports a feasibility study of making coconut fibre reinforced corrugated slabs for use in low cost housing particularly for developing countries. The casting technique for production of corrugated slabs is discussed. Flexural tests have been carried out on corrugated slabs to determine their strength with different volume fractions and aspect ratios of fibres. Tests to determine the thermal and acoustic properties of these slabs are also reported. The experimental results are presented and discussed.
Article
Comprehensive test data are presented on the mechanical properties of carbon fibre reinforced cement composites made with short random fibres of low elastic modulus obtained from pitch. Four types of cement matrices were used, and the effect of fibre volume on flow characteristics, unit weight, tensile and compressive stress strain behaviour and flexural behaviour was studied. The results showed that the properties were very much influenced by both the fibre volume and the properties of the matrix. The ultimate flexural strength was predicted theoretically and compared to experimental data.
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